Lochte is not the world's fastest man. He's not a sprinter, he's a middle distance swimmer, and FS probably isn't even his best stroke. The media should not be saying the US lost because of his "inexperience" in the relay. It's not inexperience, he's just not that fast at 100 m.
Having said that, he was probably one of the four fastest men on the U.S. team. He is one of the world's fastest at 200 m, so he can't be that bad at 100 m. I doubt replacing him with someone else would have altered the outcome. It might not have been a good idea to have him swim anchor, though.
The 4 x 100 is always the relay that is most difficult for the U.S. to win. Their prospects are much better in the other two relays. Lochte and Phelps are much better at 200 m, and they have elite swimmers in all four strokes for the medley relay, which most other nations don't have.
The brilliance of Phelps has provided a false impression that swimmers can excel at any distance and any stroke. In the past it would have been almost unthinkable that someone world class at the IM, particularly the 400 IM, could also be a top freestyle sprinter. You never saw guys like Alex Baumann or Tom Dolan swimming in FS relays. IM swimmers are generalists. They are very good at each of four strokes, but generally not world best at any one stroke, or at best maybe one stroke. Just to win one IM, let alone both, is an enormous accomplishment, and in the past would have been considered the mark of one of the best all around swimmers in the world, something like the decathlon in track (though that requires a wider variety of athletic ability than the IM). Phelps, remarkably and uniquely, is or was world class in three strokes--fly, backstroke and FS--but even in his case, only at 200 m in the latter two. Lochte is world best in the backstroke, and a strong contender in the FS, but like Phelps, only at the 200 m distance. It is asking far too much of these guys to be better than everyone else at the 100 m FS, though even then they are good enough to be on the relay.
The Hitch said:
in 08 the strongest swimmer and world record holder lost his leg to the weakest swimmer on the American team, having started with a huge advantage.
Though 2008 was an embarrassing loss for France, Lezak was not the weakest swimmer on the U.S. team. He was considered one of the strongest, that was why he was anchor.